A typical gas turbine engine has an annular axially extending flow path for conducting working fluid sequentially through a compressor section, a combustion section, and a turbine section. The compressor section includes a plurality of rotating blades which add energy to the working fluid. The working fluid exits the compressor section and enters the combustion section. Fuel is mixed with the compressed working fluid and the mixture is combusted to thereby add more energy to the working fluid. The resulting products of combustion are then expanded through the turbine section. The turbine section includes a plurality of rotating blades which extract energy from the expanding fluid. A portion of this extracted energy is transferred back to the compressor section via a rotor shaft interconnecting the compressor section and turbine section. The remainder of the energy extracted may be used for other functions.
The rotor assembly of the gas turbine engine includes a rotating disk to which the rotor blades are attached. In addition to the rotor blades, the disk may provide support for other rotating structure such as seal runners and sideplates. The size and weight of the disk is dependant upon the loads required to be supported by the disk. The rotational forces inherent to the rotating disk magnify the loads many times. The size and weight of the rotor assembly directly affects the output of the gas turbine engine, with additional weight or inertia lowering the operating efficiency of the gas turbine engine.
Much research and development has gone into reducing the loads on turbine disks to thereby minimize the size of the turbine disk. Turbine structural components have been designed to be lighter by using higher strength and lower density materials. In addition, the rotor assembly and associated components have been configured to reduce the size at the turbine disks.
Sideplate assemblies have also been a source of research and development. A typical sideplate assembly performs several functions. An example is disclosed in U.S. Pat. No. 4,701,105, issued to Cantor et al and entitled "Anti-Rotation Feature for a Turbine Rotor Faceplate". First, the sideplate shields the disk from direct contact with hot working fluid. Second, the sideplate provides passages for a flow of cooling fluid along the forward face of the disk and into the rotor blade. The sideplate functions to protect the disk directly, and the rotor blade indirectly, from the adverse effects of heat transferred from the hot working fluid. The sideplate assembly, however, adds to the loading of the disk and therefore requires the disk to be larger to support the sideplate assembly.
The above art notwithstanding, scientists and engineers under the direction of Applicants' Assignee are working to develop lightweight turbine rotor assemblies to maximize the operating efficiency of gas turbine engines.